EVALUATION OF THE FRACTURE RESISTANCE OF CAD/CAM MONOLITHIC LITHIUM DISILICATE CROWNS OF THREE DIFFERENT MANUFACTURERS: « AN IN VITRO STUDY».

Description :

AIM of this study: is to assess in vitro the Fracture Resistance of three different LDGC CAD/CAM monolithic crowns in the Premolar region. A single preparation will be carried out on a first maxillary Premolar of a study model ANA-4© (Frasaco, Tettnang, Germany) according to preparation guidelines of a full-ceramic crown. The preparation will be scanned with an optical scanner TRIOS 3 (3Shape, Copenhagen, Denmark). Thirty digital abutments will be fabricated by a Form 2, 3D printer (Formlabs Inc., Somerville, MA, USA). A crown will be designed with the Dental System (3Shape, Copenhagen, Denmark) software, and used to mill 30 crowns (CORiTEC one; imes‐icore, Fulda, Germany), 10 for each different brand of LDGC: 1-IPS e.max CAD (Ivoclar Vivadent, Schaan, Liechtenstein) 2-Upcera UP.CAD LiSi CAD/CAM block (Shenzhen, Upcera Dental Technology Co., Ltd) 3-Aidite Cameo Lithium disilicate blocks CAD/CAM (Aidite,QinhuangdaoTechnology Co., Ltd. Qinhuangdao, China) Before cementation, the dies will be sandblasted (Microetcher IIA®, Danville Materials, CA, United States) with aluminum oxide (Al2O3) for 20 s. Each lithium disilicate crown will be etched with 5% hydrofluoric acid (IPS Ceramic Etching Gel, Ivoclar Vivadent) for 60 s then rinsed and dried with an air/water syringe. A silane (Monobond Plus, Ivoclar Vivadent) is going to be applied for 60 s and dried by an air syringe. The crowns will be cemented to the preparations using the Multilink automix self-adhesive resin cement (Ivoclar Vivadent) (steps described in paragraph 16.2). The fabricated ceramic crowns will be exposed to an artificial aging process, 5000 cycles of thermal cycling between 5°C and 55°C, with an immersion time of 40 seconds.(8) The ultimate fracture load for each specimen will be measured with a universal testing machine (YLE® GmbH Waldstraße 1/1a, 64732 Bad König, Germany).